Snowthrower with removable self-heating starter battery pack

ABSTRACT

A snowthrower includes an internal combustion engine and a starter battery pack that provides electrical power to operate an electric starter motor. The starter battery pack is received within a receptacle of the snowthrower and is selectively coupled to the starter motor to initiate operation of the internal combustion engine. The starter battery pack can further include a battery heating circuit that is operable to heat the starter battery pack above ambient temperatures to increase the current output of the starter battery pack. The battery heating circuit includes a controller that utilizes electrical power from the starter battery pack to heat the starter battery pack.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is based on and claims priority to U.S.Provisional Patent Application Ser. No. 61/943,030 filed on Feb. 21,2014 and U.S. Provisional Patent Application Ser. No. 62/031,196 filedon Jul. 31, 2014, the disclosures of which are incorporated herein byreference.

BACKGROUND

The present disclosure relates to a starter battery pack tar use withoutdoor power equipment, such as a snowthrower. More specifically, thepresent disclosure relates to a self-warming circuit that uses powerstored within the starter battery pack to heat the starter battery packto increase the output, especially at low operating temperatures.

The use of snowthrowers (or snowblowers) by both commercial andresidential operators is common for those located in snowy winterclimates. These snowthrowers may be walk-behind units or may bepropelled by other machinery (e.g., all-terrain vehicles, tractors,etc.). Typically, snowthrowers are divided into two categories:single-stage snowthrowers and multi-stage snowthrowers. Single-stagesnowthrowers generally incorporate an impeller assembly that is drivenby an internal combustion engine (or similar prime mover, such as anelectric motor) to perform the functions of propelling the snowthrowerforward, lifting snow from the surface to be cleared, and ejecting thesnow out of a discharge chute. Alternatively, a multi-stage snowthrowercomprises a separate auger assembly and impeller assembly. Both theauger assembly and impeller assembly are driven by an internalcombustion engine (or similar prime mover). The auger assembly rotatesnear the surface to be cleared in order to lift and direct snow anddebris to the impeller assembly, which rotates along an axisperpendicular to the axis of rotation of the auger assembly. Theimpeller assembly then acts to eject snow out of a discharge chute.

Conventionally, the engines of both single-stage and multi-stagesnowthrowers have been started using recoil rope-pull starters. Thesetypes of starters require the operator to physically pull a rope tostart the engine. In fact, multiple rope pulls are often required beforethe engine begins to run, particularly during cold weather. Suchphysical interaction necessary to start the engine is generallyundesirable, as some operators may not be capable of using a rope-pullstarter even once, let alone multiple times.

As an alternative to rope-pull type starters, some snowthrowers areequipped with electric starter motors that are selectively coupled to ageared flywheel to initiate starting. However, a disadvantage of thistype of electric starter system is that it generally requires a 110Vcorded electric input to provide the electricity to run the starter.This dictates that the operator be near a suitable electrical outlet(and have a suitable electrical cord) at the time of starting if theywish to utilize the electric starter functionality. Given the variety oflocations in which snowthrowers are used, this is not always the case.

Accordingly, it would be advantageous to have a snowthrower capable ofbattery powered electric starting. Since lead acid batteries suffer fromsignificant disadvantages when not used for extended periods of time orin cold environments, a lithium ion starter battery pack is acontemplated replacement for a 110V corded electric input to provide theelectricity to run the starter. Lithium ion starter battery packs can beconfigured to generate the required high starting current and can heeasily recharged. However, the output of a lithium ion starter batterypack significantly decreases as the ambient temperature decreases. Thus,a solution that also increases the output of the starter battery pack atlow ambient temperature would be a significant advancement.

SUMMARY

The present disclosure relates to a starting system for outdoor powerequipment, such as a snowthrower. The starting system includes anelectric starter motor that receives a supply of electricity from astarter battery pack. In one embodiment of the disclosure, the starterbattery pack includes a plurality of individual battery cells. Thebattery cells are preferably lithium ion battery cells that combine toform the starter battery pack.

The starter battery pack is received within a battery receptacle formedas part of the snowthrower. The battery receptacle provides a point ofelectrical connection between the starter battery pack and the startermotor. An activating device, such as but not limited to a key switch,resistive or capacitive touch sensor or push button, is positionedbetween the battery receptacle and the starter motor. Movement of theactivating device to an activated position provides electricity from thestarter battery pack to the stoner motor to start the internalcombustion engine.

The starting system of the present disclosure can further include abattery heating circuit that operates to heat the starter battery packabove ambient temperature. Heating the starter battery pack aboveambient increases the current output of the starter battery pack, whichallows for the starter motor to start the internal combustion engine. Inone embodiment of the disclosure, the battery heating circuit includes aresistive heating pad that is positioned in close physical proximity tothe individual cells of the starter battery pack. When a controllerdetermines that heating of the starter battery pack is required, thecontroller connects the starter battery pack to the resistive heatingpad to heat the starter battery pack.

In another embodiment, the battery heating circuit includes at least oneenergy storage device, such as a capacitor. When the controllerdetermines that the starter battery pack needs heating, the controlleractuates one or more switches or other similar solid state switchingdevices, such as transistors or MOSFETs, to connect the battery cells tothe energy storage device or devices. The flow of electrons from thebattery cells to the energy storage devices causes the temperature ofthe battery cells to increase, which heats the starter battery pack.Once the engine has started, the controller adjusts the position of theswitches to discharge the energy storage devices back to charge thebattery cells. In this manner, the flow of electrons heats the batterycells without overly discharging the starter battery pack.

Various other features, objects and advantages of the invention will bemade apparent from the following description taken together with thedrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings illustrate the best mode presently contemplated of carryingout the disclosure. In the drawings:

FIG. 1 illustrates a single-stage snowthrower with a removable starterbattery panel in accordance with an exemplary embodiment;

FIG. 2 illustrates a top view of a single-stage snowthrower withremovable starter battery pack and panel in accordance with an exemplaryembodiment;

FIG. 3 illustrates a side view of a single-stage snowthrower withremovable starter battery pack and panel in accordance with an exemplaryembodiment;

FIG. 4 illustrates a front view of a single-stage snowthrower withremovable starter battery pack and panel in accordance with an exemplaryembodiment

FIG. 5 illustrates a top view of a single-stage snowthrower panel withremovable starter battery receptacle in accordance with an exemplaryembodiment;

FIG. 6 illustrates a single-stage snowthrower panel with removablestarter battery and battery receptacle in accordance with an exemplaryembodiment;

FIG. 7 illustrates a rear view of a single-stage snowthrower panel withremovable starter battery receptacle coupled to a wiring conduit inaccordance with an exemplary embodiment;

FIG. 8 illustrates a lithium ion (Li-Ion) starter battery pack with aheating pad installed;

FIG. 9 illustrates the heating pad integrated between the individualcells of the starter battery pack;

FIG. 10 illustrates one embodiment of a circuit used to self-heat thestarter battery pack;

FIG. 11 illustrates a second embodiment of a circuit used to self-heatthe starter battery pack;

FIG. 12 illustrates a third embodiment of a circuit used to self-heatthe starter battery pack;

FIG. 13 is a fourth embodiment of a circuit used to self-heat thestarter battery pack;

FIG. 14 is a fifth embodiment of a circuit used to self-heat the starterbattery pack; and

FIG. 15 is a graph illustrating how the internal resistance of thestarter battery pack increases with a temperature drop.

DETAILED DESCRIPTION

Referring to FIG. 1, a single-stage snowthrower 100 is shown. While thefollowing description relates to a single-stage snowthrower and itscomponents, the concepts described herein are also applicable tomulti-stage snowthrowers and other types of outdoor power equipment thatincludes an internal combustion engine and is used in cold weatheroperating conditions. Snowthrower 100 comprises an impeller housing 102having are impeller therein The impeller rotates at a high speed (e.g.,1100 rpm) to both lift and throw snow away from the snowthrower unit andpropel snowthrower 100 forward along a desired path. The operator pushes(or pulls) the snowblower along that desired path via a handle assembly103, wherein the user pulls engagement bar 118 to enable the impeller torotate. Snow that is lifted by the impeller is thrown from a rotatablechute 104, wherein the direction of the rotatable chute 104 ismanipulated by the operator via a chute direction control 108. Othermeans of rotating chute 104 are also possible (i.e., by hand, viamotorized rotation, etc.).

Snowthrower 100 further comprises an internal combustion engine 106 usedo drive the impeller and/or drive wheels of the unit internal combustionengine 106 may be a horizontal shaft or vertical shaft engine.Conventionally, engine 106 is started via a recoil, rope-pull starter110. As described above, the operator must pull on the rope to start theengine. However, in accordance with the exemplary embodiment,snowthrower 100 further comprises an electric starter motor (not shownwhich utilizes electrical energy provided by a removable starter batterypack mounted within a panel 112. As will be described in more detailbelow, the removable starter battery pack is received in a batteryreceptacle on panel 112 for easy operator access and greater overallfunctionality.

FIG. 2 and FIG. 3 show a top view of panel 112 on snowthrower 100. Panel112 comprises a mourning receptacle for a starter battery pack 114Although the starter battery pack 114 is shown as being removable fromthe receptacle, the starter battery pack 114 could be mourned to thesnowthrower and recharged in place. In the embodiment shown, the starterbattery pack 114 is preferably a lithium ion (Li-Ion) battery that iscapable of being retained in the mounting receptacle via one or moreknown methods (e.g., sliding engagement, latched engagement, etc.).However, starter battery pack 114 could comprise any suitable batterychemistry. The starter battery pack 114 acts as a starting battery forproviding electrical energy to an electric starter motor mounted on theinternal combustion engine. When an activating device, such as arotatable key switch 116, is turned by the operator, electrical energyfrom the removable starter battery pack 114 is delivered to the electricstarter motor. The electric starter motor operates to start the internalcombustion engine. Alternatively, other activating devices operable toinitiate the electric starter motor and starting the engine arepossible, such as a resistive or capacitive touch sensor, a push-buttonlocated on panel 112, or a push-button incorporated into removablebattery pack 114 itself, etc.

As removable starter battery pack 114 is conveniently located on panel112, the operator can easily remove the starter battery pack 114 if andwhen it requires recharging. Alternatively, the starter battery pack 114could be received in a receptacle positioned at other locations on thesnowthrower, such as on the frame, the shroud or even on the engine. Inan embodiment in which the starter battery pack 114 is not removable,the starter battery pack would be recharged in place on the snowthroweror other outdoor power equipment. As described above, a main deterrentfrom the use of batteries to power electric starter motors onsnowthrowers and other cold-weather outdoor power equipment was thetendency for batteries to have increased internal resistance whichlimits current flow in such low temperatures.

Referring to FIG. 4, a front view of panel 112 on snowthrower 100 isillustrated. A light 120 is mounted on the front of panel 112 toilluminate the path of snowthrower 100. Light 120 may be powered byremovable starter battery pack 114. In fact, removable starter batterypack 114 may also power other electrical loads on the unit, such as amotor-driven chute, etc.

FIG. 5 and FIG. 6 show a battery receptacle 122 on panel 112. Removablestarter battery pack 114 is slidably engaged within battery receptacle122 such that battery pack 114 is secured on panel 112. Others types ofengagement are also within the scope of this concept. Battery receptacle122 has a plurality of electrical contacts 124 which are electricallyconnected to at least the starter motor (via a wiring conduit 126 shownin FIG. 7) to deliver electrical power to the electric starter motor ofengine 106. Starter battery pack 114 has a plurality of comparableelectrical contacts 128 that mate with contacts 124 of receptacle 122.The configuration of these contacts may vary and could be somethingother than physical contacts (inductive, etc.).

In accordance with another exemplary embodiment, the starter batterypack 114 may also be configured to be a security device to preventunauthorized starting of the snowthrower 100 or other outdoor powerequipment. That is, starter battery pack 114 may be electronicallyconfigured to be unique to the particular piece of equipment that it isto be mounted to, not unlike a garage door opener or remote-entry fobfor a vehicle. A transmitter associated with the starter battery pack114 may sync to a receiver located on the piece of equipment to bestarted to allow for a “handshake” authorization to start the engine ofthe equipment. Thus, not only can the operator ensure that the enginewill not be started if a battery is not mounted to the appropriatereceptacle, but the equipment may further limit the particular batteryused to start the engine. This configuration provides greater securityand ensures that only authorized use of the equipment is possible.

Although a lithium ion starter battery pack 114 provides the requiredcurrent (150-200 amps) and voltage for operating the electric startermotor of a snowthrower, lithium ion battery packs suffer from areduction in the amount of current they can generate as the ambienttemperature decreases. As shown in the graph of FIG. 15, the poorperformance of Li-ion batteries at subzero temperatures has been linkedto a significant increase in internal resistance at low temperatures. Atenfold increase in resistance relative to room temperature has beenmeasured for cells at −20° C. This increase in the internal resistanceresults in a reduction in the amount of current that can be generated bythe lithium ion starter battery pack, which reduces the effectiveness ofthe starter battery pack in cold weather climates, which is theenvironment where most snowthrowers and other types of outdoor powerequipment including internal combustion engines are utilized. In orderto address this problem, the present disclosure provides a self-warmingsystem that allows the lithium ion battery pack to heat itself prior toproviding current to the electric starter motor used with thesnowthrower.

FIG. 8 provides one illustrative example of a lithium ion starterbattery pack 114 used in accordance with the present disclosure. Thelithium ion starter battery pack 114 includes multiple cells 131 and thestarter battery pack 114 can be received in a receptacle on thesnowthrower, as previously described.

FIGS. 8 and 9 illustrate a heating pad 130 that can be placed in closephysical proximity to or in direct contact with or interwoven betweenthe individual cells 131 of the lithium ion battery pack 114. Theheating pad 130 is activated to supply heat by receiving a source ofelectricity through a cable 132 and associated plug 134. When electricalpower is provided to the plug 134, internal resistive elements containedwithin the heating pad 130 generate heat. When the heating pad 130 ispositioned in contact with the lithium ion starter battery pack 114, theheating pad 130 elevates the temperature of the battery pack relative toambient.

FIG. 10 illustrates one circuit and system that can be utilized as aself-heating circuit for the lithium ion starter battery pack. As shownin the system diagram of FIG. 10, the lithium ion battery 140 isconnected to an electric starter motor 142 of the snowthrower through astarting switch 144. The position of the starting switch 144 iscontrolled by the controller 146 through a control line 148. When thecontroller doses the switch 144, current and voltage from the lithiumion battery 140 is supplied to the electric starter motor 142. Uponreceiving such current, the starter motor 142 activates and starts theinternal combustion engine 145 of the snowthrower. Once the internalcombustion engine 145 has started, the controller 146 again opens theswitch 144 to interrupt the flow of power from the battery 140 to thestarter motor 142.

As shown in FIG. 10, the controller 146 is connected to a temperaturesensor 150 and a start button 152. When the user depresses the startbutton 152, the controller 146 reads the current value of thetemperature sensor 150 to determine whether the self-heating functionfor the battery 140 is required. If the controller 146 determines thatthe temperature is below an ambient temperature threshold, thecontroller closes the self-heating switch 154. When the self heatingswitch 154 is closed, current from the lithium ion battery 140 flowsthrough the heating pad 130.

As illustrated in FIG. 10, the heating pad 130 includes a series ofresistive elements 156 connected in parallel with each other across thebattery 140. When the switch 154 is closed, current flows through theresistive elements 156, which generates heat. As discussed previously,the heating pad 130 can be positioned in contact with the starterbattery pack, which heats the individual cells of the starter batterypack. The heat applied to the starter battery pack increases the outputof the individual cells of the starter battery pack. Once thetemperature of the starter battery pack has been elevated, the starterbattery pack can generate the required amount of current, which can beapplied to the electric starter motor 142 through the switch 144. Inthis manner, the lithium ion battery pack can self-heat. Although theself-heating process will result in a slight reduction in the storedcapacity of the starter battery pack, the heating of the battery packwill increase the output of the battery pack to a sufficient level tostart the snowthrower.

FIG. 11 illustrates a second embodiment of a starting circuit inaccordance with the present disclosure. As with the embodiment shown inFIG. 10, the starting circuit includes a controller 146 coupled toreceive signals from both a temperature sensor 150 and the start button152. The controller 146 controls the position of the switch 144 tosupply power from the battery 140 to the electric starter motor 142. Inthe embodiment shown in FIG. 11, the battery 140 includes threeindividual cells 131 that are selectively connected to a storage circuit160 rather than to a heating pad as in the embodiment of FIG. 10. Thestorage circuit 160 includes a pair of capacitors 162 a and 162 b thatare connected in series with each other. The first capacitor 162 a isconnected between a first switch 164 and a second switch 166. The secondcapacitor 162 b is connected between the second switch 166 and a thirdswitch 168. The switches 164, 166 and 168 are each controlled by thecontroller 146 through control lines 170. The two capacitors 162 a, 162b allow the battery pack 140 to discharge electrons that are then storedby the capacitors based upon the position of the switches 164, 166 and168. By connecting, disconnecting and switching connections, current canbe directed into and out of the individual cells 131. For example, the10.8 volts from the battery 140 can be discharged from the threeseparate cells 131 into the two capacitors 162 a, 162 b. Then, currentfrom the charged capacitors can be directed back into the cells torecharge the cells. The controller selectively positions the switches164, 166 and 168 to keep the cells 131 balanced. The controller 146functions to prevent the cells from getting unbalanced (i.e., by keepingthe voltage of the cells within approximately 0.3 volts of each other).

As an example, when switches 164, 166 and 168 are in the positions shownand switch 144 is open, voltage from the cell I begins to chargecapacitor 162 a, while cell 2 and cell 3 begin to charge capacitor 162b. Discharging of the capacitors is also controlled by the position ofswitches 164, 166 and 168. The pair of capacitors 162 a, 162 b storeelectric power from the battery pack 140. The movement of electrons fromthe battery pack 140 to the capacitors 162 a, 162 b causes theindividual cells 131 of the battery pack 140 to begin to heat. Thus,unlike the embodiment shown in FIG. 10, the embodiment of FIG. 11utilizes the movement of electrons from the battery pack 140 to thecapacitors 162 a, 162 b to heat the battery pack 140.

Once the battery pack 140 has reached a required temperature, thecontroller 146 moves the switches 164, 166 and 168 into the desiredpositions and closes the switch 144 to provide power from the batterypack 140 to the electric starter motor 142 to start the engine 145. Oncethe engine 145 has started, the switch 144 is opened to prevent furtherdischarge of the starter battery pack 140.

After the engine starts, the controller 146 moves the switches 164, 166and 168, which allows the charged capacitors 162 a, 162 b to begin torecharge the battery 140. Thus, the stored charge on the battery is notlost and is instead used to both charge the battery 140 and provideadditional power to the electric starter motor 142.

FIG. 12 illustrates yet another embodiment in which the storage circuit160 is comprised of only a single capacitor 172. The single capacitor172 is charged by the string of three cells 131 (10.8 volts). Byconnecting, disconnecting and switching connections created by theswitches 174 and 176, current can be directed into and out of the singleand dual cell strings. For example, 10.8 volts can be discharged fromthe three cells into the capacitor 172. Thereafter, some current fromthe 10.8 volt charged capacitor 172 could be directed back into cells 2and 3 to recharge the cells. Selectively positioning the switches 174,176 could then direct charge into cells 1 and 2, and then finally anyremaining charge can be directed into the individual cells 1, 2 or 3 tokeep the cells balanced. As with the embodiment of FIG. 11, the movementof electrons from the individual cells 131 to the storage capacitor 172will heat the cells 131.

FIG. 13 illustrates yet another embodiment for self-heating the battery140 formed by the three cells 131. In this embodiment, the cells 131 areconfigured and connected through a series of switches a-f that arecontrolled by the controller 146. The controller can selectivelyposition the switches a-f such that the cells can charge and dischargebetween themselves without the need for any external capacitors or anyother type of electron storage device. The design shown in FIG. 13requires multiple switches a-f to control the flow of electrons betweenthe cells 131. As with the embodiment of FIG. 11, the movement ofelectrons from the individual cells 131 to the storage capacitor 172will heat the cells 131.

FIG. 14 illustrates yet another embodiment for self-heating the battery140. In the embodiment shown in FIG. 14, the controller 146 controls theposition of a switch 175 through a control line 179. When the switch 175is closed and the switch 144 is open, electrons from the battery 140flow through the resistor 178. The resistor 178 is sized such that onlya relatively minimum amount of energy is wasted through the resistor178. The flow of electrons from the battery 140 to the ground throughthe resistor 178 causes the battery 140 to increase in temperature.

In the embodiments shown in FIGS. 10-14, various different circuits areillustrated that allow the lithium ion battery pack to self-heat due tothe flow of electrons and, in the case of FIG. 10, through an externalheating pad. Although embodiments are illustrated, it is contemplatedthat the hardwire connections could eventually be replaced with wirelessconnections and the b of switches, capacitors and battery cells couldchange depending on design considerations.

All of the concepts shown in the drawing Figures require amicrocontroller or logic circuit to control the switches and to insurethat the cells stay balanced. The microcontroller is often used toprovide lithium-ion battery management. The microcontroller or logiccircuitry would also monitor temperature and may only engage the warmingfunction when necessary below a threshold temperature). Lowertemperatures would dictate an increase in electron cycling to generateadditional warming.

It is contemplated that the self-warming circuit shown in the drawingsmay operate utilizing several different control schemes. In oneembodiment, the self-warming circuit will engage independently when thetemperature drops below a threshold value, even if the start button hasnot been depressed. In this embodiment, the battery will warm to anoptimal temperature and wait for the start button to be depressed.Although this type of operation may waste energy, it would insure thatthe battery pack is ready to start the snowblower before the userdepresses the start button.

Alternatively, the self-warming circuit could warm the battery pack toan intermediate temperature and wait for the start button to bedepressed. Upon activation of t start button, the battery pack would bewarmed to the optimal temperature prior to starting. This embodimentwould conserve electron transfer as compared to the embodiment thatwarmed the battery pack to the optimal temperature during ultra coldtemperature.

In yet another alternate embodiment, the control system would wait fortine start button to be depressed and only then warm the battery pack.After the battery pack is warmed, the engine starter would be cranked tostart the engine. This control scheme would slightly delay the enginestarting after the start button was depressed.

Although the present disclosure has been described with reference toexample embodiments, workers skilled in the art will recognize thatchanges may be made in form and detail without departing from the spiritand scope of the defined subject matter. For example, although differentexample embodiments may have been described as including one or morefeatures providing one or more benefits, it is contemplated that thedescribed features may be interchanged with one another or alternativelybe combined with one another in the described example embodiments or inother alternative embodiments. Because the technology of the presentdisclosure is relatively complex, not all changes in technology areforeseeable. The present disclosure described with reference to theexample embodiments and set forth in the following definitions ismanifestly intended to be as broad as possible. For example, unlessspecifically otherwise noted, the definitions reciting a singleparticular element also encompass a plurality of such particularelements.

This written description uses examples to disclose the invention,including the best mode, and also to enable any person skilled in theart to make and use the invention. The patentable scope of the inventionis defined by the claims, and may include other examples that occur tothose skilled in the art. Such other examples are intended to be withinthe scope of the claims if they have structural elements that do notdiffer from the literal language of the claims, or if they includeequivalent structural elements with insubstantial differences from theliteral languages of the claims.

We claim: 1-20. (canceled)
 21. A snowthrower comprising: an internalcombustion engine; an impeller rotatable by the internal combustionengine; an electric starter motor coupled to the internal combustionengine to start the internal combustion engine; a battery receptaclemounted on a handle of the snow thrower; and a removable starter batterypack including a plurality of lithium ion battery cells surrounded by anouter housing, wherein the outer housing of the starter battery pack isreceived in the battery receptacle positioned on the snowthrower,wherein the battery receptacle electrically couples the removablestarter battery pack to the starter motor to provide electric power tothe starter motor to start the internal combustion engine.
 22. Thesnowthrower of claim 21, wherein the battery receptacle is mounted in acontrol panel mounted to the handle of the snowthrower.
 23. Thesnowthrower of claim 21 further comprising an activating deviceselectively operable to electrically couple the starter battery pack andthe starter motor.
 24. The snowthrower of claim 23 wherein theactivating device is a push-button switch.
 25. The snowthrower of claim21 wherein the starter battery pack and the battery receptacle areuniquely associated with each other.
 26. The snowthrower of claim 21further comprising: a battery heating circuit electrically coupled tothe starter battery pack, wherein the battery heating circuitselectively heats the starter battery pack to elevate the temperature ofthe starter battery pack; and an activating device operable toselectively electrically couple the starter battery pack to the batteryheating circuit to heat the starter battery pack and to selectivelycouple the starter battery pack to the electric starter motor throughthe battery receptacle.
 27. The snowthrower of claim 26 wherein thebattery heating circuit includes a controller coupled to the activatingdevice and operable to selectively supply electric power from thestarter battery pack to heat the starter battery pack.
 28. Outdoor powerequipment comprising: an internal combustion engine; an electric startermotor coupled to the internal combustion engine to start the internalcombustion engine; a battery receptacle; and a removable starter batterypack including a plurality of lithium ion battery cells surrounded by anouter housing, wherein the outer housing of the starter battery pack isreceived in the battery receptacle, wherein the battery receptacleelectrically couples the removable starter battery pack to the startermotor to provide electric power to the starter motor to start theinternal combustion engine.
 29. The outdoor power equipment of claim 28further comprising an activating device selectively operable toelectrically couple the starter battery pack and the starter motor. 30.The outdoor power equipment of claim 29 wherein the activating device isa push-button switch.
 31. The outdoor power equipment of claim 28wherein the starter battery pack and the battery receptacle are uniquelyassociated with each other.